A lawmaker has told the BBC that bodies littered the streets of Bama, a northern Nigerian town two days after it was seized by militant Islamists.

Boko Haram fighters were patrolling the streets of Bama, preventing people from burying the dead, Ahmed Zanna said, despite claims by the Borno government that the town had fallen.Officials said about 26,000 people had been displaced by fighting in Bama, a key town in the battle for control of Nigeria’s north-eastern Borno state.

Earlier this week, the Nigeria Security Network (NSN) think-tank said the group had made “lightning territorial gains” in recent months, raising fears that the country could disintegrate like Syria and Iraq, where the Islamic State (IS) rebel group has declared a caliphate. ‘Fought gallantly’Boko Haram has also said it has set up a caliphate in the areas it controls – it is not clear if the two groups are allied.

Mr Zanna, a senator in Borno, said the humanitarian situation in Bama was “terrible” and there had been a “lot of killings” in the town.

“So many bodies litter the streets, and people are not allowed to even go and bury the dead ones. So the situation is getting worse and worse,” Mr Zanna told the BBC’s Newsday programme after speaking to a resident who fled the town.

Boko Haram has captured a string of towns in northern-eastern Nigeria in recent months, fuelling concern that it could advance towards the main city, Maiduguri.

Mr Zanna said it would be “catastrophic” if Boko Haram launched an assault on Maiduguri, which has a population of more than two million.

“I’m begging the government to send more troops and armoury to Maiduguri,” he said.“Boko Haram do come overwhelmingly because they recruited en masse in the villages [in Borno state],” he added.